nats.erl
A simple NATS client library for Erlang/OTP.
This project is still WIP. Any of the implementations, including exported APIs, may change drastically and frequently.
Features
-
Connecting to a NATS server
- A subscriber receiving messages (publish/subscribe)
- A subscriber receiving messages (request/reply)
- A publisher sending messages
- Keep-alive (PING/PONG) handling
- Unsubscribing
- Using TLS
-
Authentications
- Token Authentication
- Username/Password credentials
- TLS Certificate
- NKEY with Challenge
- Decentralized JWT Authentication/Authorization
Usage
See Subscriber/Publisher examples for details.
%% Start gen_server with network info.
{ok, Pid} = natserl:start_link(#{name => <<"natserl">>, % any name unique per connection
remote_address => Host, % server address
remote_port => P, % server port
ping_interval => 1000 % interval to send PING
}),
%% Connect to your NATS server.
%% Info has the contents of INFO message from the server.
{ok, Info} = natserl:connect(Pid),
%% Subscribe or publish with required parameters.
ok = natserl:subscribe(Pid, Subject, SID),
ok = natserl:publish(Pid, Subject, Message),
%% After subscribing, received messages are sent to your Pid.
receive
Msg ->
io:format("Received: ~p~n", [Msg]),
end
%% Or you can receive messages on the Pid you specify.
Receiver = spawn(fun() -> your_message_handler() end),
natserl:receive_on(Pid, SID, Receiver),Running examples
Compile everything first in the project root.
rebar3 compile
Run the subscriber example.
Params: <server address> <server port> <subject> <sid>.
$ example/subscribe.escript 127.0.0.2 4222 test.abc "SID"
Connected to server: #{client_id => 4,client_ip => <<"127.0.0.1">>,
go => <<"go1.17.1">>,headers => true,
host => <<"0.0.0.0">>,max_payload => 1048576,
operation => 'INFO',port => 4222,proto => 1,
server_id =>
<<"NAQYDOL7KUQNF2LUS46JWIC6L6OA65MOHC2H4DNCMUV3TNRXSFV5KE47">>,
server_name =>
<<"NAQYDOL7KUQNF2LUS46JWIC6L6OA65MOHC2H4DNCMUV3TNRXSFV5KE47">>,
version => <<"2.6.2">>}
Waiting for messages...
Received a message: #{num_bytes => 9,operation => 'MSG',
payload => <<"Hi there!">>,reply_to => undefined,
sid => <<"SID">>,subject => <<"test.abc">>}
Waiting for messages...
Then run the publisher example on another terminal session.
Params: <server address> <server port> <subject> <message>.
$ ./example/publish.escript 127.0.0.2 4222 test.abc "Hi there!"
Connected to server: #{client_id => 5,client_ip => <<"127.0.0.1">>,
go => <<"go1.17.1">>,headers => true,
host => <<"0.0.0.0">>,max_payload => 1048576,
operation => 'INFO',port => 4222,proto => 1,
server_id =>
<<"NAQYDOL7KUQNF2LUS46JWIC6L6OA65MOHC2H4DNCMUV3TNRXSFV5KE47">>,
server_name =>
<<"NAQYDOL7KUQNF2LUS46JWIC6L6OA65MOHC2H4DNCMUV3TNRXSFV5KE47">>,
version => <<"2.6.2">>}
Published a message "Hi there!" with subject "test.abc"
You'll see the received message on the subscriber's session. It is a map that consists of all the fields of a MSG operation.
Received a message: #{num_bytes => 9,operation => 'MSG',
payload => <<"Hi there!">>,reply_to => undefined,
sid => <<"SID">>,subject => <<"test.abc">>}
Waiting for messages...
Author(s)
Yoshiyuki Kurauchi (Website / Twitter), with a lot of help from my teammates in Working Group Two.
We're always open to welcome co-authors! Please feel free to talk to us.
